1. Field of the Invention
The present invention relates to a flexible printed circuit on a surface of which a wiring pattern is formed, and a semiconductor device using it.
2. Description of the Related Art
FIG. 6 is a schematic representation of an example of a prior art semiconductor device. This semiconductor device has a main substrate 101, and first and second multi chip modules (hereinafter, referred to as xe2x80x9cMCMxe2x80x9d) 103, 105 are electrically connected to this main substrate 101 by connecting methods such as a leadless chip carrier and BGA (ball grid array).
In the first and second MCMs 103, 105, a plurality of IC chips (not shown in the figure) are COB(chip on board)-mounted on a circuit substrate (not shown in the figure). The COB mounting is a mounting method in which a bare chip is directly mounted on the substrate, an electrode of a bare chip is connected to an electrode of a substrate through a wire, and the chip is over-coated by a resin.
Hitherto, the MCM in which a plurality of IC chips are COB-mounted on the circuit substrate is used in the above-described prior art semiconductor device, and the mounting area is increased as the number of IC chips to be mounted is increased, and the size of the MCMs 103, 105 is also increased. The increase in the mounting area causes a trouble in reducing the size of an electronic product provided with the above-described semiconductor device.
The first and second MCMs 103, 105 are solder-mounted on the main substrate 101 by the BGA or the chip carrier. Such an MCM is disadvantageous in that the re-workability from the main substrate 101 is poor. Re-work means a work to mount the MCM on the main substrate after the MCM is detached from the main substrate for repairs, etc.
The present invention is achieved considering the above-described circumstances, and an object thereof is to provide a flexible printed circuit and a semiconductor device in which the mounting area can be considerably reduced when a plurality of semiconductor elements are mounted. Another object of the present invention is to provide the flexible printed circuit and the semiconductor device excellent in re-workability.
To solve the above-described problems, the flexible printed circuit of the present invention has a wiring pattern formed on the face side thereof, and is characterized to comprise a first area part, a second area part which is provided continuous to the first area part, folded to the first area part side, and has at least one electronic parts mounted thereon, and a third area part which is provided continuous to the first area part and folded to the second area part side.
The above-described flexible printed circuit has the second area part on which at least one electronic parts is mounted, the second area part is folded to the first area part side, and the third area part is folded to the second area part side. The mounting area can thus be considerably reduced compared with a prior art multi chip module using a substrate which cannot be folded. The electronic parts here are a generic term of semiconductor elements and peripheral elements.
The flexible printed circuit of the present invention preferably includes a connector terminal which is provided continuous to the first area part and connected to a main substrate. The multi chip module can thus be easily attached/detached to/from the main substrate, and the re-workability can be improved.
The flexible printed circuit of the present invention has an area on which an external terminal is provided on a rear side of the first area part.
The semiconductor device of the present invention comprises the flexible printed circuit having the first area part, the second area part provided continuous thereto, and the third area part provided continuous to the first area part, a wiring pattern formed on a face side of the above-described flexible printed circuit, and an electronic parts mounted on at least one of the face side of the second area part and the third area part, wherein the second area part is folded to the face side of the first area part, and the third area part is folded to a rear side of the second area part.
In the above-described semiconductor device, the electronic parts is mounted on at least one face side of the second and third area parts of the flexible printed circuit, and since the flexible printed circuit is folded, the mounting area can be considerably reduced compared with the semiconductor device using a prior art substrate which cannot be folded.
The semiconductor device of the present invention preferably further includes the peripheral element mounted on at least one face side of the second and third area parts. The electric characteristics of the module can be optimized. The peripheral element includes a chip capacitor, a chip resistor and a quartz.
The semiconductor device of the present invention preferably further comprises a connector terminal which is provided continuous to the first area part and connected to the main substrate. The semiconductor device can be easily attached/detached to/from the main substrate thereby, and the re-workability thereof can be improved.
The semiconductor device of the present invention further includes an external terminal provided on a rear side of the first area part.
In the semiconductor device of the present invention, it is preferable that the face side of the first area part is fixed to the face side of the second area part by an adhesive material, and the rear side of the second area part is fixed to the face side of the third area part by an adhesive material.
In the semiconductor device of the present invention, at least one of the second and third area parts is provided with a folded portion folded to a face side of the first area part, and the peripheral element is disposed on the folded portion.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.